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At least 217 records · Page 12Linked to original sources
PubMed2001

[DRE-PCR (Double Repetitive Element-Polymerase Chain Reaction)--a new molecular-epidemiologic method in the detection of tuberculosis].

In a pilot study Double Repetitive Element-Polymerase Chain Reaction 20 clinical isolates of Mycobacterium tuberculosis from Guatemala and 49 strains from Prague were typed. This technique is based on direct evidence of repetitive elements IS6110 or PGRS and does not require DNA purification, digestion by endonuclease nor Southern blot hybridization. Preliminary examination of Guatemalian strains revealed a striking identity or similarity of DRE-PCR profiles while the Prague strains were characterized by conspicuous polymorphism. The Prague strains were examined in a total number of 13 series of electrophoreograms and subsequently subjected to automated analysis with GelCompar software. The DRE-PCR method is suitable for screening of a major number of clinical isolates of M. tuberculosis in laboratories equipped with a minimum of technical facilities for the PCR method, furthermore it requires facilities for synthesis of the necessary primers and at least basic knowledge of molecular biology.

Bacterial Typing Techniques↗
PubMed1998

[Knowledge of physicians and dentists about biomathematical-epidemiologic methods].

A multiple-choice test questionnaire on statistical terms and methods was sent to 600 randomly selected physicians and dental surgeons and was returned by 264 (27%) of them: 183 physicians and 81 dental surgeons. The median number of correct answers for physicians was 10.1, markedly higher than the 6.2 scored by dental surgeons. At least half of the questions were correctly answered by 60% of the physicians and nearly 14% of the dental surgeons. Whereas some 14% of physicians had a good knowledge of statistical methods (with more than 2/3 of questions answered correctly), this was true of only 2.5% of the questioned dental surgeons. The results suggest that the majority of physicians and dental surgeons, especially the latter, are not capable of profiting from statistically orientated scientific articles. Moreover, the low percentage of questionnaires returned by dental surgeons may well indicate that, as a group, their statistical skills are far lower than even the results of this questionnaire would indicate. A need is seen for the education of dental surgeons to be bound more closely to that for human medicine.

Computational Biology↗
PubMed2000

Reporting of occupational and environmental research: use and misuse of statistical and epidemiological methods.

OBJECTIVES: To report some of the most serious omissions and errors which may occur in papers submitted to Occupational and Environmental Medicine, and to give guidelines on the essential components that should be included in papers reporting results from studies of occupational and environmental health. METHODS: Since 1994 Occupational and Environmental Medicine has used a panel of medical statisticians to review submitted papers which have a substantial statistical content. Although some studies may have genuine errors in their design, execution, and analysis, many of the problems identified during the reviewing process are due to inadequate and incomplete reporting of essential aspects of a study. This paper outlines some of the most important errors and omissions that may occur. Observational studies are often the preferred choice of design in occupational and environmental medicine. Some of the issues relating to design, execution, and analysis which should be considered when reporting three of the most common observational study designs, cross sectional, case-control, and cohort are described. An illustration of good reporting practice is given for each. Various mathematical modelling techniques are often used in the analysis of these studies, the reporting of which causes a major problem to some authors. Suggestions for the presentation of results from modelling are made. CONCLUSIONS: There is increasing interest in the development and application of formal "good epidemiology practices". These not only consider issues of data quality, study design, and study conduct, but through their structured approach to the documentation of the study procedures, provide the potential for more rigorous reporting of the results in the scientific literature.

Bias↗
PubMed2006

A community outbreak of tuberculosis in Southern Austria: lessons learned for a targeted use of molecular epidemiological methods and tuberculin skin testing.

A cluster of 10 cases of tuberculosis disease (one of them extrapulmonary) occurred from July 2001 until November 2003 in a health district in Southern Austria. Eight patients were culture confirmed and shared an identical strain. One of these eight cases was identified as outbreak-related by molecular strain typing only. Due to public pressure, a further 600 persons received chest X-ray and clinical examinations. Apart from one case which could be excluded from the outbreak because of a different strain pattern, no outbreak-related case of active tuberculosis was detected by this non-targeted procedure. Tuberculin skin testing, not part of the Austrian routine protocol of contact investigation in adults, was initiated after diagnosis of case 8. Forty-nine latently infected contacts were detected. Population-based genotyping of all isolates, prioritization of contact investigations and early use of targeted tuberculin skin testing are critical for effective tuberculosis control in low-incidence countries.

Adolescent↗
PubMed2005

Leveraging existing databases to study vehicle crashes in a combat occupational cohort: epidemiologic methods.

BACKGROUND: The US military is a large, well-defined occupational cohort offering tremendous opportunities to study risk factors for important health outcomes. This article describes our nested case-control methods to evaluate risk factors for fatal motor vehicle crashes (MVC) within all Service branches in a 1991 Gulf War era cohort. METHODS: We identified 1,343 cases of fatal MVC between 1991 and 1995 that were also included in the Department of Transportation's Fatality Analysis Reporting System database and, using risk set sampling, selected 13,430 controls. Our final analytic dataset consisted of 980 male driver cases and 12,807 controls linked to multiple databases. RESULTS: Cases were disproportionately younger, less educated, not married, enlisted, and deployed to the Gulf War, compared to controls. CONCLUSIONS: The ability to leverage multiple databases to study risk factors for fatal MVC is clearly advantageous and could eventually lead to the reduction of fatalities in similar occupational cohorts.

Accidents, Occupational↗
PubMed1995

Historical cohort investigation of spontaneous abortion in the Semiconductor Health Study: epidemiologic methods and analyses of risk in fabrication overall and in fabrication work groups.

The risk of spontaneous abortion (SAB) in the semiconductor industry was examined in a historical cohort study of pregnancies at 14 companies. We identified female employees who had worked for at least 6 months and whose ages ranged from 18 to 44 years during the 1986-1989 study period. Using company records, we included all fabrication-room (fab) employees and an approximately equal number of nonfabrication (nonfab) employees, for a total sample of 7,269. Telephone interviews with 6,088 women (84%) identified 904 eligible pregnancies and 113 SABs. Exposure classification was based on questionnaire and industrial hygiene assessments of tasks the women performed during the first trimester of pregnancy. Using logistic regression to control for age, smoking, ethnicity, education, income, year of pregnancy, and stress, we found a higher risk of SAB in fab employees than in nonfab employees (15.0% of fab pregnancies ended in SAB vs. 10.4% of nonfab pregnancies, adjusted relative risk [RR] = 1.43, 95% CI = 0.95-2.09). Analysis of fab work groups showed that the highest relative risk was in masking employees (17.5% SAB rate, adjusted RR = 1.78, 95% CI = 1.17-2.62 in comparison with nonfab employees). Within masking, the highest risk was found in etching-related process employees (22.2% SAB rate, adjusted RR = 2.08, 95% CI = 1.27-3.19 in comparison to nonfab employees.

Abortion, Spontaneous↗
PubMed1999

A community outbreak of Legionnaires' disease linked to hospital cooling towers: an epidemiological method to calculate dose of exposure.

BACKGROUND: From July to September 1994, 29 cases of community-acquired Legionnaires' disease (LD) were reported in Delaware. The authors conducted an investigation to a) identify the source of the outbreak and risk factors for developing Legionella pneumophila serogroup 1 (Lp-1) pneumonia and b) evaluate the risk associated with the components of cumulative exposure to the source (i.e. distance from the source, frequency of exposure, and duration of exposure). METHODS: A case-control study matched 21 patients to three controls per case by known risk factors for acquiring LD. Controls were selected from patients who attended the same clinic as the respective case-patients. Water samples taken at the hospital, from eight nearby cooling towers, and from four of the patient's homes were cultured for Legionella. Isolates were subtyped using monoclonal antibody (Mab) analysis and arbitrarily primed polymerase chain reaction (AP-PCR). RESULTS: Eleven (52%) of 21 case-patients worked at or visited the hospital compared with 17 (27%) of 63 controls (OR 5.0, 95% CI : 1.1-29). For those who lived, worked, or visited within 4 square miles of the hospital, the risk of illness decreased by 20% for each 0.10 mile from the hospital; it increased by 80% for each visit to the hospital; and it increased by 8% for each hour spent within 0.125 miles of the hospital. Lp-1 was isolated from three patients and both hospital cooling towers. Based on laboratory results no other samples contained Lp-1. The clinical and main-tower isolates all demonstrated Mab pattern 1,2,5,6. AP-PCR matched the main-tower samples with those from two case-patients. CONCLUSION: The results of our investigation suggested that the hospital cooling towers were the source of a community outbreak of LD. Increasing proximity to and frequency of exposure to the towers increased the risk of LD. New guidelines for cooling tower maintenance are needed. Knowing the location of cooling towers could facilitate maintenance inspections and outbreak investigations.

Adult↗
PubMed1976

Is Hodgkin's disease infectious? Discussion of an epidemiologic method used to impute that it is.

A method proposed by MacMahon for the differentiation between familial and environmental causes for disease has recently been applied to demonstrate an environmental etiology for Hodgkin's disease. It is shown that the method, which depends on the comparison of time-of-onset differences with age-at-onset differences for familial pairs with disease, is biased toward results suggestive of an environmental etiology when applied to data of the kind typically analyzed--data restricted to instances in which both members of a familial pair develop disease in a specified, limited time interval. Other features of such data are discussed.

Age Factors↗
PubMed1990

Epidemiological methods to study the interaction between HIV infection and other sexually transmitted diseases.

Numerous studies performed over the past 5 years have indicated an association between HIV infection and other sexually transmitted diseases (STDs), particularly those involving genital ulceration. Such an association may be causal, indicating that STDs increase susceptibility to, or infectivity of, HIV infection or may result, in whole or in part, from the mutual dependence of HIV and STDs on patterns of sexual activity, or from an effect of HIV infection on the clinical course of STDs. In this paper we discuss the issues arising in the design and analysis of studies conducted to investigate this association. A numerical illustration is used to demonstrate non-causal associations that may arise in observational studies due to confounding and misclassification. Published cross-sectional and longitudinal studies are reviewed, and recommendations made for future studies. Special emphasis is given to the use of randomized intervention trials to overcome many of the biases associated with observational studies, and to provide information on the efficacy of intensive STD treatment programmes in reducing the transmission of HIV.

Cross-Sectional Studies↗
PubMed2005

Temperature and mortality among the elderly in the United States: a comparison of epidemiologic methods.

BACKGROUND: Time-series analyses have been used for decades to investigate time-varying environmental exposures. Recently, the case-crossover design has been applied to assess acute effects of air pollution. Our objective was to compare time-series and case-crossover analyses using varying referent periods (ie, unidirectional, ambidirectional, and time-stratified). METHODS: We examined the association between temperature and cardiorespiratory mortality among the elderly population in the 20 largest metropolitan areas of the United States. Risks were estimated by season and geographic region in 1992. We obtained weather data from the National Climatic Data Center and mortality data from the Division of Vital Statistics. Conditional logistic regression (case-crossover) and Poisson regression (time-series) were used to estimate the increased risk of cardiorespiratory mortality associated with a 10 degrees F increase in daily temperature, accounting for dew-point temperature and other potential confounding factors. RESULTS: In the time-stratified case-crossover analysis, the strongest associations were found in the summer; in the Southwest, Southeast, Northwest, Northeast, and Midwest, the odds ratios were 1.15 (95% confidence interval=1.07-1.24), 1.10 (0.96-1.27), 1.08 (0.92-1.26), 1.08 (1.02-1.15), and 1.01 (0.92-1.11), respectively. Mostly null or negative associations were found in the winter, spring, and fall. The ambidirectional case-crossover and the time-series analyses produced quantitatively similar results to those from the time-stratified analysis. The unidirectional analysis produced conflicting results. CONCLUSIONS: Inferences from studies of weather and mortality using the ambidirectional or time-stratified case-crossover approaches and the time-series analyses are comparable and provide consistent findings in this study.

Aged↗